Wrong Audio BitRate using "Custom" Flash Output

[RobertJay Profile Private message]

I'm struggling with a strange behavior of PSG when I'm using the Flash Output "Custom" Video Bitrate to render my shows in MPEG4 Video format (for Flash Player 9+).

Both "Video bitrate" and "Audio bitrate" can be precisely tuned in the popup panel, but...

... when I use this panel to set both video rate and audio rate to my liking, the audio bitrate of the rendered output falls invariably down to 30kbits or so, whatever audio bitrate I enter (128 Kbit, 320 Kbit, etc...)

Has someone already faced this problem? Is there a workaround? For the moment, I'm using virtualdub to replace the audio track with a correct one I generate separately using other output options.

Thank you all in advance!